Perfect Fifth
by MixItUp
Summary: Leonard and Sheldon have a beautiful new neighbor. Too bad that Leonard already has a girlfriend. AU from pilot. Sheldon/Penny. Multi-chapter. COMPLETE.
1. P5

PERFECT FIFTH

* * *

It is just another ordinary day for Leonard and Sheldon.

Indian food in hand, the two physicists climb the stairs. Their conversation is fairly lively, though forgettable for anybody lacking an eidetic memory. Suddenly, Leonard widens his eyes and nudges his companion.

"New neighbor?"

The door is open, revealing a pretty blonde. She is wearing less clothes than the weather requires. Leonard briefly misses his life of singlehood but shakes this off quickly. Even before Elaine he wouldn't have had the confidence to approach this beautiful girl.

Sheldon's eyes flit up and down quickly, memorizing her form. He rationalizes that taking in her appearance effectively will prove useful; no doubt, he will pass her on many a morning or afternoon. "Evidently," he says. He hopes that his physiological reaction—increased heart rate, dilated pupils, et cetera—will go unnoticed by Leonard.

Leonard opens his mouth for a second, but before he can vocalize his thoughts, the woman notices them. Her bright eyes seem friendly. "Oh, hi!"

"Hi," Leonard replies, taken off guard.

Sheldon's blue eyes are wide as he greets the woman. His lips stumble over the words, and the time flashes by until her door is closed. Puzzled, he frowns. This sensation is new—never before has he experienced difficulty speaking to, well, anybody. Is it possible that somehow, through contact with Koothrappalli...

"We should have invited her to lunch," Leonard says finally.

Sheldon looks at him. "Why? I was under the impression that one only offered food to females that one had a reproductive interest in. Please do not tell me that you are considering ending your relationship with Elaine. I simply cannot stomach another five weeks of your so-called 'emo music'."

He shakes his head fervently and pushes his glasses back up. "No! Just...I don't know. She seems nice. Do you...I mean, do you mind?"

Incredulous, the other man arches an eyebrow. "Mind? Are you asking if I would feel somehow disrupted by another individual interfering with our routine, consuming time that would otherwise be dedicated to more worthy pursuits, and potentially catalyzing another unintelligent reaction from your hormones that would lead to months of misery?"

"Uh…" Leonard begins, unsure. It's possible that Sheldon has suddenly learned sarcasm, he thinks to himself. "Yeah."

Sheldon considers this, incredibly quick brain scanning through a list of possibilities. Although his rational reasoning finds that the outcome was much more likely to be unpleasant, he is unable to stop his mind's eye from displaying the image of the woman...Penny, she called herself. He swallows, unfamiliar sensations creeping up his neck, and, realizing that Leonard is still waiting on an answer, gives a brief sigh. "I suppose not."

"Great!" Leonard enthuses, a genuine smile spreading over his face. "So go ask her."

Sheldon sputters. "Me?" he asks, indignant. "I believe that as this was _your_ experiment, you should carry it out."

The other man looks at him. Slowly, he grins. "Elaine might take that as a sign that Penny—this really, _really_ attractive woman—is a sexual threat."

Leonard knows that this is a language that Sheldon understands. The men share a long look, fraught with silent conflict and—at least on Leonard's side—halfway-thought prayers. The taller physicist gives a brief nod. "Very well," he says, obvious reluctant. He straightens even further and approaches the door.

Consciously, Sheldon is aware that there is no rational reason for him to feel uneasy. This woman is nothing to him. She is, admittedly, attractive, but he set such things behind him prior to his pubescence. Male-female dynamics were complicated, and could distract him from his true love: his work. And, he thinks, even if he was searching for a viable mate, Penny, obviously very desirable by most standards, would most likely view herself as above him. Although he is incredibly aware of the importance of his intelligence and accomplishments (and considers himself, if such things matter, a man of above average attractiveness), he has also consumed enough pop-cultural dramas and psychological journals to recognize that she would be considered "out of his league". Mentally, he huffs. As if any goal was above his drive and talent.

Still, the thought is somewhat depressing, and he refuses to consider this further as he raps at her door. "Penny," he says softly, an unpleasant sensation tickling his spine and tightening his throat.

She opens the door before he reaches the third set of knocks, a fact that rather irks him. Still, she has no reason to know his habits. Sheldon halfway hopes that she will never have cause to learn them.

"Hi," she says brightly, drawing out the last syllable. He notices that her hair is more tousled than before, presumably from her labor. "Sheldon, right?"

"Uh, yes." She has caught him off guard, and he curses himself for this. A female—a woman—nobody had affected him this strongly since his adolescence, and he was no less awkward than he had been at that time. "Penny," he adds, remembering a snatch of social conduct. She offers him a smile in return.

Sheldon attempts to phrase the question in a manner that she will appreciate. "I was wondering if you would enjoy eating lunch with Leonard and myself? We have already purchased Indian food, and it is not inconvenient for us to share this with you. Also, if you happen to be a fan of the acclaimed series _Battlestar Galactica_, and have not yet viewed the second season with commentary, I would be delighted to allow you to stay and watch the episodes with us."

Leonard watches with some amusement. Penny seems to have been taken off guard; she glances from Sheldon to Leonard and back again, but something is shining in her eyes. She smiles and replies, and something in her words tips him off. The way she sidles up to him, keeping her eyes trained on his except when she looks coyly away...there's attraction there, to be sure. He almost pities her, having seen other women try to start down that path with his unreceptive roommate. Then he catches a glimpse of Sheldon's face.

While, as usual, his expression is mostly indecipherable, a slight smile is tugging at the tall man's lips, and his eyes are bright in a way that Leonard only ever sees when Sheldon is engrossed in his work...or Star Trek. It's all he can do not to gape as Sheldon actually leans forward and rests his arm on the door to speak to Penny.

"Well, you really should begin with the first season," Sheldon explains seriously. "Still, if you insist, I will hardly deny you of your privilege to partake in an excellent series, unorthodox methods aside."

Penny can't help but smile, brushing away the tingles of a too-familiar sensation. She reminds herself that the last thing she needs is another man in her life, but his disarming blue eyes are creeping under her skin. Anyway, he's far too skinny for her, though he's got a nice height. Her heart does an unbidden little leap.

Still, she's not looking for love, or even (for once) a cheap hook-up. Somehow, she doubts that this man would settle for less than commitment, and she's not up for that right now. Friendship, though, that she can handle. She flashes him another smile, this one fully intentional, and accepts his invitation.

Maybe she tosses her hair over her shoulder flirtatiously. It hardly matters; he wasn't watching, anyway.

* * *

"Wow, this looks like some serious stuff," Penny breathes. Sheldon feels a puff of pride and turns to her. He had not expected her to appreciate his work—the women in his family never had, and he hesitated to call most of the CalTech females "women", especially that she-beast Leslie Winkle. "Which one of you did this?" She gestures to his whiteboard.

For this, she receives a genuine smile. "That's my work," he tells her, leaning against the whiteboard. Sheldon feels strange, in a way similar to how he imagines caffeine or alcohol might make him feel. Had he unknowingly ingested some substance? Normally, this thought would cause a rush of panic, but the overwhelming sense of calm (accompanied by anxiety, most mysteriously) keeps this feeling at bay.

Penny blinks her (objectively pretty) eyes and takes a closer look at the whiteboard. "Wow."

"Yeah, well, it's just some quantum mechanics," he says, and for some reason he knows that it's vastly important to him that she _cares_. Impressing people is second nature to Dr. Sheldon Cooper, prodigy in every way; getting them to care about what he does, well, sometimes he does not dwell on that. "With a little string theory doodling around the edges. That part there, that's just a joke, it's a spoof of the Bourne-Oppenheimer approximation."

She nods, peering at the incredible mass of numbers and symbols. Math had scared Penny ever since high school, but she knows that without stuff like this, electronics would be impossible. She wonders briefly what Sheldon really does, but she's afraid to ask and not understand, so she just smiles. "So you're like one of those...beautiful-mind genius guys?"

The man almost blushes. Huh, a shy guy. Who'da thunk. "Yeah," he says in response, looking up at her from beneath lashes to kill for.

Leonard watches in amazement. He was a scientist, and he couldn't deny the evidence before his eyes, although it contradicted everything he knew. Sheldon Cooper was most assuredly flirting with Penny. A strange, quick urge seizes Leonard. He wants to bring the attention back to himself, to remind the beautiful woman currently staring at his roommate that _hello_, _I'm a brilliant scientist, too. _

Then his mind sweeps back to Elaine, with her long dark hair and pouty lips. The way her face lights up when she laughs. Her passion for her legal work.

Leonard smiles and settles for simply watching the pair.

* * *

Sheldon blinks several times. "I suppose that the food will be cooling to room temperature."

"Yeah, we should eat," Penny agrees. Her stomach rumbles quietly, and she tries not to think about the last time she ate—or what the last thing even was. She has a sinking feeling that she blew another diet.

They all take seats. She notices that Sheldon seems very quick to take the end cushion, but she doesn't mind sitting next to him in the middle. It strikes her as a little awkward that Leonard takes the armchair. Maybe he has some sort of personal space problem.

She nearly moans as she lifts the food to her mouth. Leonard catches her expression and gives her a weird look. In response, she shoots him a playful glare.

Somehow the conversation gets around to her lack of a working shower. Leonard looks at Sheldon significantly. "Ask her," he mouths, raising his eyebrows.

The other man frowns slightly, cocking his head to the left. "Ask her what?" he replies silently. Penny hides a smile behind her fork full of food.

"Shower," Leonard returns, with some exasperation. Sheldon purses his lips, makes an unpleasant expression, and turns to Penny. It's Leonard's turn to conceal his grin.

"Penny," Sheldon says conversationally, as if they've known each other for years. "Would you like to utilize our shower, then?"

"Could I?" The blonde woman smiles, eyes lighting up. "I mean...would that be too weird? I don't want to like, intrude or whatever..."

His lips twitch. "N-no. There would be no...weirdness."

She looks at Leonard, who tries his best to look serious. "Is that okay?"

"What? With me? Yeah, sure, of course." He nods enthusiastically, unable to stop smiling. Great, she probably thinks he's some sort of pervert. It was just too hilarious to see Sheldon actually _trying_ to get along with another person.

"Great! Thanks, I really appreciate it." Penny stands, stretching slightly. Her back is a little sore, and she rotates a shoulder to try and fix it.

"Penny?"

She looks back at Sheldon. "Yes?"

"Just confirming—you do plan on retrieving your personal cleansers, shampoos, et cetera?" His expression is one of genuine concern.

Not sure what to make of this, Penny offers another smile. "Of course, Sheldon. Going right now."

"Okay. Good."

"Yeah."

She begins to make her way to the door.

"Oh, I suppose I should retrieve a spare towel," Sheldon says, to nobody in particular. Leonard makes a gesture, as if to give him a go-ahead, but his roommate isn't even looking.

A few minutes later, Sheldon finds himself pacing nervously around the apartment. The sounds of the shower are impossible to ignore. He frowns to himself. Why has he never experienced this difficulty with Leonard? He feels very much not himself, for his mind keeps straying. Sheldon has trained his brain perfectly, to the standards of a performing animal; now, he seems more like a goldfish. The same concept returns to him, the thought of perhaps electing to leave behind his life of celibacy, and, well...

She is _very_ attractive.

He does not think this within merely physical terms. Yes, she is pleasing to the eye, but there is more to Penny than that. This was immediately obvious to him. She was captivating, somehow interesting although he couldn't care less about the mundane details of her life. Simply the way she said the words made him want to listen attentively, filing away every tiny nugget of information.

On top of all of this, his stomach is strangely unsettled. Indian Food Day may be on its figurative last legs.

* * *

Leonard does not bother to hide his smile now, as his roommate paces back and forth. He knows that Sheldon is completely wrapped up in his thoughts, though he can only guess at the contents. He drifts back to the blonde currently in the shower and smiles. She may end up being the perfect fifth member of their group, after all.

* * *

_End Notes: This will be a five-chapter story, with each chapter title being based on a musical interval. The intervals will decrease in size as we go along. Special thanks to bigbangtrans for posting the episode transcripts, of which I made liberal use. _


	2. Plus 4

PERFECT FIFTH

* * *

Penny emerges from the shower, her body covered only by the towel lent to her. She sighs in relief—it was nice to be less sweaty and gross. She wipes off the mirror and peers at her face. Rubs at the straying makeup a bit.

Deciding that she looks good enough, she pushes open the door and strides into the hallway, only to be faced with four gaping men.

Well, whoops.

"Penny," Sheldon says, and she gives him silent kudos for successfully keeping his eyes on her face after that first brief double-take.

"I'm clean," she replies awkwardly, suddenly conscious of the clump of clothes clutched in her right hand. She tightens her grip and smiles.

One of the two new guys is approaching her. Definitely the kind she'd give a fake number, if she felt nice enough to not just outright reject him. He might be a nice guy, she reflects, but he definitely sends off that creepy vibe—

"Howard Wolowitz. It's a pleasure to meet you. I'm the man who's going to make you a _very_ lucky Penny." He raises his eyebrows suggestively.

Yep, definitely creepy.

Leonard groans inwardly and glances at Raj. The astronomer looks, as usual, shell-shocked by the presence of a woman. As one, they turn to Sheldon.

Sheldon, who for once seems almost self-conscious. He is watching the exchange between Howard and Penny as intently as if it were written by Joss Whedon himself, but he makes no move to interrupt.

Leonard clears his throat loudly. His roommate does not turn.

He coughs.

"Dear Lord, Leonard, if you insist upon contracting an illness in my presence, the smallest courtesy would be to cover your mouth when you expel your filthy bacteria," Sheldon says, without turning.

Raj's lips tremble with laughter.

Leonard coughs again, more loudly. Sheldon snaps around. "Leonard, I believe that I asked you to—"

He indicates Penny with a jerk of his head. "Wolowitz," he replies, in a stage whisper.

The thought seems to connect, finally. Sheldon glances down at his hands, and then rises.

"—so if you ever need anybody to, you know, _shine 'er up_, I'm qualified for the position," Wolowitz pronounces sleazily. Sheldon is now standing near the pair. He notices how Penny's eyes flick up to his when he approaches, but he does not understand the reason. More theorizing will be necessary to make sense of this woman, to be sure.

"Well, uh, that's a-a nice offer, but I really don't," Penny fumbles, eyes returning to his. He does not understand the social protocol, but he is very confident in what he personally desires, so he settles for that.

Sheldon tries his best to give her a pleasant smile. "Penny, would you like to accompany me on a walk?"

"A walk?" she repeats, in a tone that could be described as incredulous. He gives her a quick nod. "Oh, yes, a walk! You know how much I...love walking. Just let me, uh, get my clothes and we'll go...for a walk."

Penny bolts.

"See you...in my dreams tonight!" Howard calls after her.

Leonard breathes out, finally.

"I think that went pretty well," the engineer adds smugly.

"For who? She's going on a _waaalk_ with Sheldon," Raj puts in, smirking slightly. "Sheldon, since when do you even go on..."

He is gone. The scientists look around, blink, shrug, and return to the regularly scheduled programming.

* * *

"Whew, thanks," Penny breathes, reaching to close the apartment door with her free hand. Sheldon looks hesitant as he steps inside. "What?"

"Aren't you going to change?" he asks, his eyes focusing somewhere above her head.

She nods. "Yeah, and then we can watch...Battle...that show you were telling me about. Together."

"But we are going for a walk," he says blankly, frowning.

Penny bites her lip and honesty wonders where this man is coming from. She had been sure that he was pulling some sort of smooth thing, which, okay, seemed pretty beyond him, but come on, a walk? "I thought that was just...an excuse."

Sheldon makes a scoffing noise. "An excuse? Naturally. I do not follow why it should then become a lie. That would just lead to the creation of more lies—where did we go? Was the weather nice? Is that hobo still living the dumpster?—and so on _ad infinitum_."

She tried to think of a response to this, but gave up and simply walked into her bedroom. "Be out in a minute."

Sheldon does his best to avert his eyes from the chaotic mess of boxes surrounding him. He reminds himself desperately that Penny had been in the process of moving. A thought strikes him. Perhaps she would appreciate aid with unpacking. After all, who better to organize this unholy catastrophe of a living room than Dr. Sheldon Cooper?

He smiles to himself as he examines the nearest box. "Living room or whatever," he reads to himself, and lifts the first item out.

The activity of sorting and placing her belongings is so engrossing that he does not notice when Penny returns. "Sheldon, what are you doing?"

He jumps, nearly dropping a framed photograph. "Good Lord, Penny," he scolds. "Such stealth is hardly necessary."

"I wasn't being stealthy, I was just...are you unpacking my stuff?"

Sheldon nods and sets the photograph down. "Wait, don't put that there," she says, frowning.

"Why not?" he asks, puzzled.

She turns slightly red. "Well, I just...I thought it would...no, you're right. It actually looks better there."

He smiles smugly.

Penny simply stares at the man in front of her. No matter what she did, she absolutely could not figure him out. Still, she thought to herself, she'd be willing to try...

No, not going there right now.

"Ready to go?"

"I have one more photograph in this box," he says absently, holding up the picture. Her heart cracks more easily than glass.

"No! Don't put that out," she nearly shouts before she can catch herself. Sheldon's blue eyes are wide with confusion.

"Why not? It's quite a well done image. Oh, are you under the impression that you appear overweight? I can see that your blouse does create that illusion, but honestly, Penny—"

She tries to force herself to breathe. "It's not that, Sheldon. Do you see the man next to me?"

"The one with his arms wrapped around you?" If Penny had been less distraught, she might have searched for a hint of jealousy in his eyes.

"Yeah. That's my ex-boyfriend, Kurt."

Sheldon considers this. The man seems intimidating, but Penny's photographed expression is no less than gleeful. "Why did you terminate your relationship?" he asks, and he is shocked to realize that they are now quite close in proximity. He could easily catch any of her diseases at this distance.

Penny sniffles. "He was a liar—and a cheater—and a jerk, and I knew it, but...I was so stupid. When he said he'd change...I believed him."

He attempts a sympathetic expression. "I have heard that people are incredibly irrational when they fall in love."

She gives him a sad smile through her tears. "It's true."

Then she performs a most unexpected action. She reaches forward with sudden force and embraces him. His immediate instinct, to escape, proves impossible. Sheldon stares down at the woman who is latched onto him, and reluctantly pats her on the back. Her body heat is causing a dramatic increase in his internal temperature. He feels positively feverish. "There, there."

Finally, she releases him, rubbing at her nose with a hand. He watches in disgust. "I'm sorry, it's just...on top of all that, he still has my TV, and I don't know how to get it back from him."

"Perhaps it would be easier to purchase a new television," Sheldon suggests gently.

She looks up at him through the tears, nearly laughing at his naivete. "Sheldon, I can't afford that. I can barely afford this friggin' apartment."

"Oh."

She sniffs again. "I'm sorry," she says again. "I don't mean to be such a...a damsel in distress, but...can you think of any way to help?"

He visibly stiffens. "A damsel in distress?"

Penny frowns. "You know, just a—"

Sheldon waves this away. "I understand. I will go at once."

She blinks. "Oh. Uh...thank you. What about our walk?"

Sheldon offers her a smug smile. "I'll have to take a rain check."

* * *

He arrives at her door a few hours later, Leonard in tow. Both men look as if they have braved a great battle, but they appear unharmed. "The TV's in the car," Leonard wheezes.

Penny squeals, sneaking a glance up at Sheldon. He returns the look, a smug, knowing gleam in his eyes. "How did you do it?" she asks breathlessly, hugging them both quickly.

Leonard opens his mouth, but Sheldon cuts him off. "Penny. We're _scientists_."

She can't decide if she wants to slap him, kiss him, or hug him again. She settles on an arm squeeze.

After they carry the TV up the stairs (she's already praying for that damn elevator to be fixed), Leonard says, "I think we should celebrate with dinner."

"Oh, the three of us?" Penny asks, with an indecipherable expression.

Leonard glances aside. "Well, we could invite Elaine and Howard and Raj if you want..."

She shrugs. It is strange how she makes the motion appear so graceful. "Whatever."

Sheldon realizes he should speak up. "That would be acceptable in my estimation."

"Uh...awesome. Okay."

Leonard tries not to sneak glances at Sheldon and Penny during dinner, but he fails miserably. It is simply so fascinating, he thinks with a smile. The way they catch each other's eye and seem to have already developed a sort of language.

With a jolt, he realizes that this is not a dinner of six. It is an intimate meal for two, with a +4 who really don't need to be there.

"Who ever thought this day would come," he says under his breath. Elaine raises her eyebrows at him, and he tries to communicate "tell you later". She nods and laughs to herself. He smiles back unconsciously. It's nice to be so easily understood.

* * *

The next day, they are consuming Thai food in the apartment when a knock sounds at the door. Sheldon jumps up through something like instinct. Leonard sits back down, an odd half-smile crossing his face.

When he opens the door, Penny is there, smiling brightly. Something is different about her eyes, he notices. Perhaps she had applied her cosmetics in another manner.

"Hey, Sheldon," she says, rather softly, and gestures.

Obligingly, he steps out into the hallway. "Penny."

"I'm not uh, interrupting, am I?" She touches her hair self-consciously.

He shakes his head. "Well, technically, yes, but I find that I do not mind. Continue."

Penny smiles, a bubble of warmth filling up her chest. "I'm having some furniture delivered tomorrow, and I'll be at work. At the Cheesecake Factory, I don't know if you remember—"

"I have an eidetic memory," he says softly. "I remember everything."

She blinks. "Oh. Well...that's really cool." Penny means what she says, and she's a little jealous. It would be nice not to eternally forget her stuff. No wonder Sheldon is so brilliant. Oh, right. She tries to get herself back on track. "Anyway, I was wondering if you'd sign for me?"

"It would be of no inconvenience to me."

"So...that's a yes?" She furrows her brow.

He smiles tightly, and the condescension is tempered with something else she can't quite understand. "Yes."

"Great. I'll, uh...let you get back to your Thai food."

Sheldon nods. "Yes. Thank you."

"Thank _you_," Penny echoes.

They stand, facing each other for a moment.

"Well...bye," she says, and scampers back to her apartment.

Sheldon stays where he is, frowning at her door. He cannot remember ever feeling this way when he spoke to anybody. It was a curious sensation, all fire tickling his breath and obstructing his breathing. A sharp intake of air.

It seemed that a new challenge had fallen into his hands.

* * *

_End Notes: The music reference in this is the +4, the symbol for the augmented fourth. Again, bigbangtrans was invaluable. I wanted to get this chapter up before tonight's episode._


	3. m3

PERFECT FIFTH

* * *

The delivery men share an exasperated glance. "Look, we took it to the address on the paper," one says, holding up his clipboard and then pointing to the package. "The rest is up to you, Dr. Cooler."

"Cooper," Sheldon replies hotly, facial muscles giving an involuntary twitch. "You did not deliver your package to the address, because the address is four flights of stairs up from this lobby. It would be advisable for you to begin carrying it now."

The second man looks at the first rather anxiously. "Maybe we should just do what Mr.—uh, Dr. Cooper wants."

"Very wise," Sheldon says approvingly, flashing a quick smile. He's found himself doing that more lately, but the cause evades him.

Reluctantly, the two men carry the package up the stairs, Sheldon following closely. A flood of pride colors his cheeks as he considers how grateful Penny will be. He definitely deserves his self-awarded title of neighbor of excellence.

He inspects her apartment when they enter. An unconscious twitch; she is still very unorganized. Sheldon loses himself in a quick fantasy of cleaning the entire apartment, but bites it back. He can worry about that later, when he has finished fulfilling his duty.

"Sheldon?"

"Hello, Leonard," Sheldon says pleasantly, turning to greet his friend.

Leonard frowns, peering around the taller man from his hallway vantage point. "What's going on?"

"Penny needed me to sign for a package. I was just ensuring that the delivery men performed their job." He says this in an offhand manner, but Leonard definitely catches the lilt in his voice when he says "Penny needed me".

"Is that okay?" one delivery man asks nervously. Sheldon casts his eyes and nods.

"Admirable job, gentleman."

"Yeah, whatever," the other man mutters, and the pair wanders down.

Leonard clears his throat. "Uh, aren't you going to leave?"

Sheldon blinks. "Oh. Yes. I was just considering a new organizational paradigm to discuss with Penny."

"I'm not sure that's the best idea..." Leonard hedges.

Sheldon looks at him. "Don't be ridiculous, Leonard. It is my prerogative to share my wealth of intelligence with others."

"Hey, guys," Penny says, and both men jump back slightly.

"Good Lord," Sheldon says, rather disapprovingly. "Are you training to be an assassin?"

She does her best to look serious. "No, that was last week. This week I'm an elderly grandma." She smirks.

They stare at her blankly. Penny sighs. "Actress?"

"Oh..."

Leonard decides to act. He gives Sheldon a significant look. "Sheldon, don't you have something to ask?"

He tilts his head slightly. "To what are you referring?"

The experimental physicist sighs and turns to Penny. Like a mother speaking for her child, he explains, "Sheldon wanted to know if he could help clean and organize your apartment."

"Leonard, I am perfectly capable of speaking for myself," Sheldon replies, twitching. More pleasantly, he adds, "Penny, would you be averse to the idea of allowing me to institute a new organizational paradigm in your living space?"

"I couldn't ask you to do that," she says, biting her lip.

He looks at her. "You're not asking me. I'm asking you."

Penny sneaks a glance at Leonard. He nods fervently. She returns her gaze to Sheldon, whose blue eyes are locked on her. "Fine. But I'll help, okay?"

A brief nod. "Very well."

"It's a date!" Penny says, and then widens her eyes, realizing what she said. Sheldon is oblivious to this, and begins babbling about the plans.

Leonard smothers his giggle.

* * *

So the weeks pass by in much this same way. Penny begins to feel more at home among the boys of 4A and their weird friends. Sheldon accommodates for her presence in the group, to the point that there might as well be scheduled Penny and Sheldon Days. Leonard, for his part, watches, smiles, and enjoys his new free time to spent with Elaine.

Everything becomes part of the new normal. That is, until the department party debacle.

Leonard had been hoping that Sheldon would ask Penny to go with him, but the thought had not even crossed the other man's mind for all he could tell. Elaine was disappointed as well; though she wasn't exactly the president of the Sheldon fan club, she was, as she put it, "pretty damn sick of being the only woman at these things".

God, Leonard loved her.

So here they are, and he just _knows_ that Sheldon is going to say something stupid. He prays he's wrong, but he doesn't keep his hopes up. Sure enough...

"My apologies for allowing my mind to wander, but I had more important things to consider than your infantile babbling."

He might have been able to get away with that, but he follows it up with, "I suppose I shouldn't bother detailing what I was considering, because it is unlikely that you are able to comprehend concepts above an eighth-grade level."

Needless to say, Sheldon comes home jobless.

* * *

_Knock knock knock_. "Penny."

_Knock knock knock_. "Penny."

She opens the door. He looks at her. She closes the door.

_Knock knock knock_. "Penny."

The door opens again. "What's up, Sheldon? You, uh...you don't look...like yourself. Are you okay?"

His smile is more forced than usual. "Oh, I feel _wonderful_. Pursuing new research opportunities."

"Really?" Penny is curious, but she's also sure that whatever he spits at her will be impossible to understand. Still, she asks. "Like what?"

"Well...currently, I am researching the life of a person who has recently been fired."

"You were..."

The look on his face says it all. She opens the door further, to let him in, and presses a hand against her mouth. "Honey, what did you do?"

"What makes you say it that way? I never said that it was my fault," he says crossly. "But I may have overstepped my boundaries at a certain departmental party."

"Oh, sweetie." As one, they take their usual seats on her couch. Instinctively, she reaches out and touches his arm. He jerks slightly, but does not pull away.

She looks at him with a warm expression, and somehow that heat transfers to his chest. Absently, Sheldon asks, "Do you have any superpowers, Penny?"

She wrinkles her nose. "What?"

"Well, to pick an entirely random example, do you have heat vision?" He watches her face carefully. Penny laughs and squeezes his arm. Her hand has moved slightly so that she is now touching him flesh to flesh. He swallows.

"Why don't you hang out with me today, then? I don't have to work until tonight." Her tone is inviting. He looks at her seriously, and then nods.

"Alrighty. We can 'hang out'."

"Great," she says, genuinely. "I know just what'll cheer you up."

The new putt-putt course wouldn't know what hit it.

* * *

Penny knows he's watching her from over his ice cream, but she pretends not to notice. Her tongue darts over the cone.

"Thank you, Penny," he says, and she can tell that he means it. She's about to smile and reply when he continues. "The past few days have been a marvelous introduction to the mundane, ordinary life...which is not to say that I did not enjoy it. What are we doing tomorrow?"

Sheldon's eyes are shining, and that little voice hiding in her heart that she's been trying to ignore for weeks is whispering about how _this is what she wanted_. Her stomach does a bizarre kind of twist and she swallows the thoughts right down.

It takes almost all of her strength (minus the tiny part of her that knows he's crazy) to brush this off and tell him. "Sheldon, sweetie, you have to go back to work."

He blinks at her, and she wonders if she should tell him about the dab of ice cream on his nose. No, she decides. It looks too cute. "Penny, that is patently untrue."

"You're not going to be happy without it," she says gently, and somehow her hand has wrapped around his. She knows it doesn't mean anything like that, but it's a drop of sunshine nonetheless. "You live for your work, Sheldon, everybody knows that. It's the only thing that makes you happy."

At this, he frowns and shakes his head. "Absolutely untrue. There are many other factors to my happiness: satisfying food, regular bodily functions, the existence of _Star Trek_. Comics. Scheduling. You."

Penny chokes on her ice cream and has to press a napkin to her face. Sheldon watches her, unmoved. She recovers. "I'm sorry, what was that last one?"

"Although you are a recent addition to my life, you have completely subsumed yourself into every facet," he says, trying his best to express his meaning clearly. "You have become an essential part of my happiness. Congratulations."

She coughs again. "Um...be that as it may...honey, you're not going to be happy just with Star Trek, comics, and me."

Sheldon nods. "Yes, you forgot scheduling, regular bodily functions, satisfying food...of course, my other friends and acquaintances are not to be forgotten. Video games, I suppose."

"None of that's going to make you happy."

He is aware that he is twitching, and he is also aware that Penny is correct in her argument. "I cannot simply ask for...Gablehauser...to return my job."

"And why not?" she challenges, and he does not want to look into those flashing eyes.

"I just...can't."

Penny half-sighs and half-groans. She stands up, right in the middle of the store, and she's almost glad that Sheldon doesn't understand social norms anyway. All of the other customers are watching her now. She doesn't care.

"Look. I haven't known you that long, but I know one thing about you, Sheldon Cooper. You are stubborn, and you are bullheaded. _Don't_ tell me I'm being redundant," she says quickly, seeing his lips beginning to move. "You are stubborn and you get what you want. You do what you think needs to be done, even if it seems...well, crazy as hell to everybody else. There is no 'can't' with you, mister. You've woken me up at four in the morning so that we could be at the comic book store before opening. You've insisted that we eat pizza on Thursday nights even when you admitted you were craving sushi. I don't know what's wrong with you, but I do know that you're not going to back down now, with something that's so important to you. Okay?"

The rest of the customers break out into hushed mumbles. She crosses her arms and glares.

"Very well," Sheldon replies, after a second of consideration. "You're coming with me."

Decisively, he stands, and throws his daintily folded napkins into the trash. His hand closes around her wrist before she registers his movement, and pretty soon they're outside.

"Sheldon, we can't go now. It's a Saturday afternoon. He's not gonna be—"

He silences her with a look. "I know where to find him."

* * *

"Sheldon, we can't go to his house!" Penny hisses.

Sheldon frowns. "I can see no evidence to support your argument. Clearly we are at his house, and look, here I go, approaching the door."

"I'm not going with you!" Her frame closes up further, which he has learned is a sign of her displeasure.

"You promised that you would be my 'moral support', as you called it," he reminds her. She groans and trails behind him. Sheldon knocks on the door.

Gablehauser opens the door, and Sheldon has no trouble picking up the cue of exasperation that crosses the man's face. "Oh. It's you. What do you want, _Dr. Cooper_?"

"My position back," he says, and he holds his hand out to anticipate the door closing. Penny is watching with an unreadable expression.

"No." Gablehauser tries to close the door, but the superior scientist is able to retain his hold.

"I should not have said what I did, please forgive me," Sheldon recites robotically. Penny can't decide if she should giggle or bury her face in her hands.

"I said, no, Cooper. Case closed."

Sheldon braces his body against the door. "You are aware that my research is invaluable and that my theories are unmatched. You must know, if you are not an absolute gibbering idiot, that I am one of the greatest minds in this country, if not the world. If you do not allow me to return to CalTech, you _will_ regret it."

Obvious hesitation colors the man's face. Penny wants to spit on him; he reminds her so much of a certain casting director who rejected her over and over just because she wouldn't sleep with him. "I'll think about it," Gablehauser says slowly. Sheldon nods and turns.

Before the door can close, Penny catches it. Quickly, she whispers, "If you don't give him his damn job back, we're both going to drive to your house every day and annoy the crap out of you."

"Are you threatening me, little cowgirl?" he asks, sneering.

She smiles. "No. If I were threatening you, I'd mention my extremely impressive record from back when I was in Junior Rodeo. My specialty was...castration."

He closes the door.

Monday morning, there is an email in Sheldon's inbox informing him that his sabbatical is over. Penny hugs him without his consent and bounces off to the Cheesecake Factory in an unusually good mood.

* * *

"Good to have you back," Leonard says, clapping Sheldon on the back. As usual, his roommate glares at the physical contact.

There are a few things different that day about Sheldon. One, his work demeanor is considerably more cheerful and outgoing, although Leonard doubts that will last. Two, when he passes Dr. Gablehauser in the hall, the two men exchange cordial smiles laced with poison.

And a minor third—the sole piece of clutter on his pristine desk is a ticket stub from the past week. Leonard grins at this, but doesn't say anything. It's gonna be interesting, he thinks, when they realize they're dating.

* * *

_End Notes: Why do I love Penny and Sheldon having it out in public? I don't know. But I do._

_Let me just say that if anybody reading this wants recommendations for Shenny fanvideos or fics, please just message me, because I have plenty that I'd love to throw at you._

_This timeline works best if you don't think too hard about it. So please don't. The interval in this chapter is a minor third, of course._


	4. M2

PERFECT FIFTH

* * *

The time ticks by, and Leonard starts to believe Elaine when she whispers that "those two idiots will never get it together". It's been long enough. Still, he does see some hints of progress here and there.

Sheldon's spot now has a dear companion, the middle seat that is marked Penny's as clearly as if her name was painted on it. Every night, they're there, so close, but then Penny goes back to whatever dumb boy-of-the-week she has and Sheldon goes back to his comic books and Leonard just wants to scream at both of them. Maybe knock their heads together, too, and hope they happen to kiss.

"Why are you getting so worked up about this?" Elaine asks on one particularly lazy afternoon. She twirls her hair with one finger, and he feels a stupid lovesick grin slipping over his lips.

Leonard tries to clear his head to answer her question. "I don't know, just...well, to be honest, I want somebody to take Sheldon off my hands."

She looks at him over her reading glasses. "What, you want them to move in together?"

He almost chokes at the thought. "No," he says hurriedly, "but I want to know that if, well...if ever I left for a-any reason, he'd be okay. You know?"

"That's kind of sweet," she replies, smiling at him a little. He winks, feeling suddenly confident, and she rolls her eyes at him.

Yeah, she's pretty much perfect.

* * *

Sheldon contemplates his dilemma as he stares at the cramped writing that covers his whiteboard. It is indecipherable to anybody but him, he made sure of that, but that is a small comfort.

The fact is completely unavoidable, and his conclusion rests soundly on his precise logic. Still, he cannot fathom what action he should take.

_Knock knock knock_. "Shelllll-don!" a voice sings out. The singing is, unfortunately, quite literal. He sighs, but he can feel his lips curl up into a definite smile. It's a Broadway day. Fridays usually are.

He waits for her to complete the sequence before opening the door. "Hello, Penny."

"Sheldon, hey," she says breathlessly, looking up at him. Dazzling. "I realized that I forgot to tell you! I'm having a party. Do you want to come?"

Sheldon considers this prospect. "What kind of party?"

"You know, a costume party. You can, uh, cosplay, you know. Or whatever you want." Penny shrugs carelessly and pretends that she isn't trying to read the thoughts hidden in those eyes (that are absolutely to die for).

Sheldon blinks deliberately and shifts his weight. She wishes she didn't notice these little things. "What will you be dressed as?" he asks, in a somewhat guarded tone.

She swallows. "I don't know. I was thinking maybe Catwoman, but...do you think I can pull it off?"

Penny has given up pretending. She knows that this little game with him has escalated, and her original attraction was definitely not a lie. He's got his quirks, all right, and more than once he's made her want to rip out her own intestines and strangle him with them, but underneath all that is a man who can make her feel really warm and fuzzy. And she hasn't felt like that—all fluffy feelings and not just lust—in a _long_ time.

She loves the feeling of his eyes slipping over her, surveying her. He purses his lips. "If you are inquiring if you would possess the same physical appeal that Catwoman traditionally does, yes, I believe that would be no obstacle. Still, I worry about the necessary materials. Cosplay halfway done is simply absurd."

"Well," she says slowly, as if thinking about it. "You could help me. If you want."

He nods wordlessly, eyes focusing on something only he can see. "I believe that it would be socially unacceptable for me to attend your function without the permission of the rest of the group."

Penny smiles. "They're invited, too."

She really has given up on pretending that Sheldon's quiet smile doesn't give her a dozen different kinds of butterflies.

* * *

Leonard almost spits out his coffee when he wanders into the living room on a Sunday morning to find Sheldon surrounded by plans, sketches, and phone numbers. These things should really stop surprising him, and he scolds himself for the reaction. "Whatcha doing?" he asks casually.

His "batcrap insane" roommate barely looks up. "Finalizing the costume data. I believe that I have found a suitable vendor who shares my ideals of true adherence to the source material."

"What costume are you going to wear?" Leonard sets his coffee down and takes the chair, which is about the only place not covered by papers. "And why didn't you use the whiteboard?"

"It was full," Sheldon says shortly. "These plans are not for my costume, but for Penny's."

He tries not to smile as he says, "Oh, okay. What's her costume?"

"Catwoman. It was her suggestion, and as you well know, I fully encourage anybody who wishes to take part in cosplay, as long as it is entirely correct. Which it will be." He finishes cutting out a rectangle of text and begins to neatly stack the remainder of the papers.

"Uh-huh, so what are you gonna be?" Leonard doesn't bother hiding his smile now.

"Batman," he answers without a thought.

Leonard looks down sneakily as he says, "You know, that's a very popular costume for couples nowadays. They really like the sexy dynamic there."

"Yes, I know," Sheldon replies, placing the stack on the table and piling up his supplies. "I found it quite an appropriate way to express my interest."

This time, Leonard does more than choke on his coffee. It's a full on spit take.

"What?" he manages to sputter, wiping the hot liquid off his chin with one hand. Sheldon sends him a disapproving glare.

"I found it an appropriate way to express my interest," he repeats in his faux patient tone. "Is that really so remarkable?"

Leonard's mind is racing. Hold on a major second, he thinks. Since when is Sheldon so candid about his feelings? Since when does Sheldon _have_ feelings? "Uh, catch me up, buddy."

Sheldon gives a heavy sigh and turns to face Leonard completely. "I noticed physiological and emotional disturbances ever since Penny's advent. Therefore, I conducted tests on my person and deduced that I was experiencing romantic feelings toward her. You may have noticed that I am no expert in the subject, having never engaged in such activities, and I would have continued in that steadfast manner. My plans were foiled, however. She is _irresistible_, Leonard," he says more quietly, almost whining. "It proved quite impossible."

He thinks back to her, all pretty blonde hair and bright green eyes and perfect figure. Any man would kill for such a prize. "Yeah, she is pretty gorgeous."

Sheldon scoffs. "Gorgeous? Honestly, Leonard, I was hardly referring to her physical features, attractive though they may be. Those I can easily resist. Harder to forget: the bright expression in her eyes when she discusses something about which she is passionate, her headstrong and determined nature, how easily she reads me, her power to make everything seem better. One might liken her unto the sun, and say that she brightens—if one were waxing overly poetic, of course. As I was saying, I am now doing my utmost to express my interest, as social norms dictate. Any questions?"

Leonard shakes his head mutely.

This was gonna be one helluva party.

* * *

It was a pretty decent party, when all was said and done. Howard nearly got kicked out for his insufferable use of cat-related puns. Raj shivered in a corner. Sheldon followed Penny like a puppy dog, and she didn't really seem to mind. Leonard...well, he just watched, and maybe he might have sneaked out after a few drinks to take advantage of a little private time with Elaine.

Time passes uneventfully. Sheldon is not concerned by Penny's lack of obvious requital; the slow pace suits him just dandy. That is not to say that he isn't pleased when she bursts into his apartment and begs to stay for awhile.

"It's just this girl I know from Omaha and she's _such_ a slut and she's hogging all my stuff and making a mess and just...I can't do it, I can't, I give up!"

He offers her a smile and her seat on the couch.

"Thanks, Sheldon." Penny plops down and slips off her shoes. Sheldon resists the urge to scold her. "You're such a good friend."

As she says this, she watches his eyes carefully. Her radar had been going off a lot lately, but from what the guys had said, Sheldon wasn't interested in people of any kind, men or women. Still, she knew that he was at least attracted to her, and if there was one thing Penny knew, it was how to distinguish like and _like-like_.

He swallows. "You're welcome."

No hints of any kind. He seems perfectly satisfied with his position as friend. She sighs inwardly and makes herself comfortable. She's gonna be here for awhile.

Howard and Raj come over, and as seems inevitable, Howard falls into the trap of the "Whore of Omaha" (as Sheldon humorously refers to her). Penny seems to enjoy this remark, and he reminds himself to make attempts at humor on a more frequent basis.

Like she has before, in events of sickness or injury, she fills in the empty spot on their Halo team. Sheldon admits privately that she does, as usual, "totally smoke" him.

When she makes the horrible discovery of Wolowitz and the Whore's tryst, Sheldon is quick to offer her room on the couch, provided she follows basic safety regulations—romance has not blinded him entirely to his priorities. He sleeps soundly, and hopes she does the same. It is the morning that proves troublesome.

Her head is resting on his spot, the quadruple-zero, the only place from which he can watch Doctor Who. Sheldon sighs gently and grabs a pillow. He carefully lifts up her head from its position to a cushion on his lap. She doesn't so much as snore.

Penny wakes up to a peculiar sense of warmth, and she's more than a little happy to find her head on (a pillow on) Sheldon's lap. She smiles, feeling the buzz of a good night's rest. "Good morning."

"Good morning," he replies, and the smile they share is at least as bright as sunshine.

* * *

When Howard's little sexcapades disturb the natural order of Chinese Food Night, Leonard expects Sheldon to throw a tantrum and refuse to proceed. Instead, he purses his lips and goes next door.

_Knock knock knock._ "Penny."

_Knock knock knock._ "Penny."

_Knock knock knock._ "Penny."

She opens the door, looking bedraggled and fed up. His eyes glance over her appearance, but he does not mention it. "Please accompany us to Chinese Food Night. We are in need of a fourth member of our party."

Penny looks back over her shoulder hesitantly and leans in closer. Sheldon does the same, with a confidential air. "On what terms?" she asks.

"We will order egg rolls, but you are not permitted to attempt to ingest them using your chopsticks," he tells her seriously.

"Very well," she says, matching his tone.

From inside the apartment, Leonard grins. Maybe progress isn't so impossible for them after all. Now, if only he could convince Elaine to take that next step with him and move in...

* * *

_End Notes: I really have to stop making all my stories end up about Leonard. He just so naturally gravitates to the role of narrator if I use him at all. The interval referenced in this is "major second". The soundtrack for this story should be up within a few days. _


	5. P1

PERFECT FIFTH

* * *

Sheldon is doing his best to care about Koothrappali's situation when Penny arrives on the scene. "Guys!" she practically screeches, before regaining her composure and hardening her countenance into what he can only assume is an impression of him. "I have found myself requiring willing test subjects for an experiment I will be conducting."

"No," Sheldon, Leonard, and Howard reply simultaneously. Raj shakes his head fervently. They know her all too well.

Penny pouts. "Please," she whines, drawing out the single syllable. "I finally got a bartending shift, and if I can pull this off it means a pay raise, but I've gotta get some practice in."

They exchange looks. Sheldon is the first to speak.

"Penny, I applaud you for your attempt at upward mobility, but perhaps we are not the best subjects for this experiment. After all, only Leonard and Howard regularly consume alcohol." His tone is somewhat soothing, but she can tell that he's just trying to save his own butt.

Raj holds up a hand and gives her a significant look. She raises her eyebrows. He nods.

"Well, it looks like Raj is up to it," she says pointedly.

Sheldon avoids her eyes, but he still feels a shock of disappointment when she sighs and concedes. He spends the next half hour watching her mix drinks and socialize with the others, and he realizes that he might need to revise his work thus far.

Instead of accompanying the others on their Cheesecake Factory expedition, he stays behind and struggles through the possible solutions. By the time that Leonard returns to regale him with boring tales of Raj's failure, he is, to put it simply, "fed up".

Sheldon has never enjoyed consulting others; he considers it generally beneath him. However, this subject is so far outside his areas of expertise that he finds himself driven to it.

"Leonard?" he asks hesitantly.

His roommate pauses whatever insignificant activity he was performing and turns around. "Yeah?"

"I want to ask you something."

Leonard looks at his roommate, who is bouncing slightly on the balls of his feet. The shorter man smiles slightly. "What is it, Sheldon?"

He opens his mouth. Closes it. Opens again. "What am I doing wrong?" he asks plaintively.

Leonard smirks. "I think you'll have to be a little more specific than that."

Sheldon sighs, relaxing his shoulders. He looks at the ground. "Penny does not seem to comprehend my expressions of interest. Additionally, she seemed displeased with me earlier when I refused to allow her to mix an alcoholic drink for me. I do not understand. Popular media is obviously deceitful: this process of wooing was never shown to be this darn hard." His Texas accent comes out on the last few words. Leonard smiles, feeling a sudden rush of empathy. It was always nice to be reminded that his roommate _was_ human, after all. No matter what he pretended.

"Sheldon," Leonard said, as gently as he could, "I think you might need to be less...well, a bit more...you need to change. Somewhat. I mean, you're really uptight and closed up about what you like. Penny...she's a really social person, and she probably isn't sure how it would work between the two of you when you're so critical and antisocial."

Sheldon blinks, taking in the words. "Let me confirm this. You're suggesting that my behavior is putting my viability as a mate into question?"

He scrunches up his face. "I...guess? I mean," he adds, translating to Sheldonese, "a reasonable amount of sociability is a desirable trait for the male of most species."

"Fascinating," Sheldon breathes. "I think you may be onto something, Leonard. Yes. That does fit the existing data. Well done."

Leonard feels a puff of pride. It was always nice to be able to do something that Sheldon couldn't, and if he actually acknowledged it...the high was practically incomparable. Hey, maybe it hadn't skipped a generation after all. He'd never really wanted to follow in his mother's footsteps, but if his analyses were always that spot-on...

"Don't get any ideas," his roommate says suddenly, as if he had been reading Leonard's mind. "It wasn't _that_ well done."

* * *

Sheldon inhales deeply. He couldn't believe that he was going to do this. His mother would definitely have his hide for it. Still, he thinks back to the beautiful equations and nods, feeling his heart swell with determination.

He strides into the bar area, takes a stool, and says with confidence. "I'd like a Cuba Libre, please."

Bravely, he adds, "And make it promiscuous."

Penny spins around, eyes wide. "Sheldon," she greets him. He does not quite recognize her tone—all light and airy, like she's giggling the word—but he finds that he rather likes it. "What are you doing here on a _Friday _night?"

Sheldon shrugs, and she almost laughs at his attempt to be casual. "I felt like being social. Also, I believe that I ordered a drink?"

"You don't drink," she says dryly.

He raises a finger. "I _didn't_ drink. Please, fetch me my beverage before I change my mind."

"Ooh-kay," Penny mumbles, turning around to mix the drinks. While she's at it, she refills her own glass, hidden under the bar. If Sheldon's drinking, there's no way she's staying this sober.

About an hour later, and he's consumed more than one promiscuous Cuba Libre. Sheldon is starting to feel quite _libre_ himself, pounding away at the keys like he only dares to do on his wildest days. He plays love songs, mostly, and the crowd seems to eat it up, but his eyes are on Penny.

She can't shake his intense stare, and it does something funny to her heart. So when he asks her to come over and do a duet with him, her heart practically stops.

"Sweetie, you hate my singing," she says, slowly.

Sheldon bobs his head. "Yes, but that does not matter. I am feeling so _liberated_, Penny! Sing with me."

His blue eyes are so wide and innocent...she can't resist. She whispers to one of her nice coworkers, and the girl just nods and takes her place. Penny slips out and over to the piano.

"I'll start," he says, in what would have been a soft voice had he not been riproaringly intoxicated. There is no introduction, but from the first few notes, she recognizes the song.

Penny realizes she's probably the only reason Sheldon even knows this one. It's a popular song, and she likes to turn the radio up all the way and sing along, pretending that she has somebody to sing it with.

Hey. Now she does.

Dutifully, she chimes in at her part. They are both slurring their words a little bit, and he slows the tempo as she trips over the words. Still, when they reach the chorus together, it is beautiful. They might both be going flat, but they're going flat together.

Their voices drift down, eyes still locked. Their harmony shifts to a perfect unison.

Suddenly, she feels very transparent and vulnerable, like her skin is just plastic wrap over all of the feelings she's been dying to keep inside. It doesn't seem so bad, though. Penny smiles. Maybe it's because he's kind of on display, too.

He grins at her and almost topples over. Yeah, she'll definitely need to help him home tonight.

* * *

"Lucky I'm in love with my best friend," a phantom croons in his ear. Sheldon squints his closed eyes and tries to speak, but his lips have been glued shut.

"P-penny?" he manages finally.

A giggle. "Yeah, it's me. You fell asleep in the car on the way home." Something warm nudges him.

Sheldon sits up, and slowly registers his surroundings. "Oh," he says shortly. She laughs again, gently.

Somehow, he finds his way up the stairs, through the door, and into his bed. He doesn't even brush his teeth before he collapses.

Penny doesn't have it so easy. She could hold her drink a lot better than he could, whether from years of practice or just natural ability, and so she was forced to lay awake. The song kept running through her head, and eventually she just got up, jammed headphones over her ears, and listened to it online. She hummed along, but her heart was going much faster than the beat.

She has it bad, and she doesn't know what to do.

The look in his eyes is plastered to her eyelids. Penny knows that she can't take this any longer, and she wants to jump for joy at the thought that those same feelings had shown on his face. Still, her heart lurches. What if it doesn't work out? Is she crazy for thinking that this could ever work?

"Penny, stop psyching yourself out," she says aloud. She likes to give herself pep talks sometimes. "You can talk to him in the morning."

Her eyes drift to the clock. 2:13. A sigh escapes her lips. It's gonna be a long night.

* * *

From the instant Sheldon's eyes blink back open, he recalls the events of the previous night. He feels somewhat embarrassed that he allowed himself to become so intoxicated, but he also remembers the way that she smiled and sang with him. It was worth it, he judges, and performed its function.

Something seems to be pressing against his head. He realizes that he must be experiencing veisalgia. He feels...well, as Penny would say, he feels like utter crap.

He stumbles out of bed and commences his morning ritual. A note on the mirror informs him that Leonard is out for the day with Elaine. Well enough, he would only have mocking words for Sheldon, anyway. The shower makes him feel marginally better, but he is still slightly nauseated and his head aches dully.

Despite all this, he feels an impetus to see her, to find out if his actions really yielded a result of consequence. Sheldon approaches his front door and pulls it open.

Penny tumbles in.

At first they're a mishmash of misplaced limbs, but when she rights herself, he is still regarding her with the same intense expression. "Penny," he says absentmindedly. She notices that his hair is sticking up messily, and fights the urge to comb through it with her fingers.

"Sheldon, hey, I was just coming to check on you. You feeling okay?" Penny presses a hand to his forehead, although why she does this she isn't quite sure. He does not brush away her touch.

He clears his throat. "I do seem to have vei—a hangover," he adds hastily. "My head is clearing, however."

"Good," she says, in a tone more breathy than her usual. His stomach responds oddly to this. "I'm sorry, babe, I should have cut you off."

"It is not your responsibility," Sheldon responds, shaking his head slightly. Her touch has moved from his forehead to his arm, but there it only rests on his shirt. He finds himself wishing for skin-against-skin contact again.

Good Lord, this business of romance really is horrifying. A few months ago, he would have never imagined a desire within him to touch anybody's bare flesh, but one brush from Penny and he can't stop swallowing and nearly hyperventilating.

Penny pulls back slightly. Sheldon seems to be getting uncomfortable, and her heart sinks a little. "Well, I'm glad you're okay," she says awkwardly.

He nods, and she turns to make an exit, but his long fingers catch her arm at the crook of her elbow. "Wait."

She looks back at him. His lips are slightly parted, but no words come out.

"Last night..." she says softly. "Do you remember trying to kiss me?"

"I have an eidetic memory," Sheldon reminds her stuffily. "I remember—"

"Everything, yeah, I know." How did he still manage to be so condescending when he was hung over? "Why did you...?"

He avoids her eyes. "I was led to believe that it was the next step after a mutual interest had been established, and it seemed that our duet performed that function. Why did you stop me?"

"Sweetie, you were drunk. I didn't know if you, you know...meant it." Feeling bold, Penny traces his jawline with her hand. He closes his eyes for a second.

When his eyelids flutter back open, his gaze is astoundingly strong. She's never been the swooning type, but that look could definitely make a weaker woman's knees buckle. "Can we attempt that again?" he asks quietly.

Instead of replying, she leans forward and kisses him.

Sheldon tastes like peppermint and innocence, with the slightest hint of rum still coloring his breath. She smiles into the kiss. He is holding her very gently and carefully, as if she might break. She hasn't had that kind of consideration from a man since...

Well, never, actually.

"I'm sorry," Leonard says helplessly, for about the fifth time. Elaine rolls her eyes at him.

"For the last damn time, Leonard, it's not your fault that your car battery went dead." She grins and snatches at his hand. "Besides, we can have a stay-in movie date at your place."

They reach the door. The handle proves unlocked, so Leonard pushes it open. After a second, he pulls it closed again, smiling slightly.

"What?" Elaine asks, raising a single eyebrow. "Sheldon in there?"

He responds by opening the door again, ever so quietly. She peeps in, laughs deeply, and closes the door again. "Never thought I'd see the day."

"I'm impressed," Leonard admits. "Lip-to-lip contact?"

She laughs again. "Whenever he caught _us_ making out, it was always, 'Leonard, are you unaware of the hordes of bacteria that can be transferred through this sort of behavior?'." Elaine's impression of the physicist is positively uncanny.

He stops laughing and holds up one hand. "Wait, I think they're talking now," he whispers. They crowd around the door.

"Sheldon Cooper, you're out of your friggin' mind if you think I'm signing a relationship contract," Penny says hotly.

Sheldon sighs heavily. "Penny, Penny, Penny, why are you being so unreasonable about this? It's a perfectly rational—"

"Rational my ass! I am not gonna sign some piece of paper that says we're dating! We're going to go about this like normal human beings, Sheldon."

Leonard and Elaine exchange a look.

"My place?" she asks in a dramatic whisper.

He nods fervently. "_Definitely_ your place."

Before they leave, he sneaks one final glance at the arguing pair. Their eyes are fierce, but still surprisingly gentle, and he wouldn't be at all surprised if they started kissing again at any moment. Leonard shakes his head. "Those crazy kids," he murmurs, smiling. He slings an arm over Elaine's shoulder and they walk off.

He even dares to whistle.

* * *

_End Notes: The interval—a perfect unison. Say it with me: awww._

_The soundtrack to this is now available on my tumblr, and the link is posted on my profile on here, so if you enjoyed the story, check it out. Thank you to all of my faithful readers, especially those of you who take the time to review! _

_If you liked this story, please read my other Shenny works! Also, I am currently working on two oneshots to be a companion to this story: _Consonant _and _Dissonant_. Keep a look out for those!_


End file.
